Please don't place any reliance on online family trees, whether on Ancestry or anywhere else.
What happens is that someone finds only one candidate in the surviving records who roughly fits their ancestor, and they assume it is the right person, even though there is absolutely no supporting evidence. Oblivious to the fact that the surviving records are incomplete, and their genuine ancestor is one who is among the missing ones, they add the candidate to their tree and publish it. Then along come 10 more people, and they find the tree and think, "Oh, good! That's my family, and someone else has done the work, so I'll just add that to my tree, and publish it!" And along come 100 more people who do the same, and before you know it there are hundreds of trees out there all containing the same wrong information. And more people come along and see that there are hundreds of trees with the same information, and they think that all those people must be right because they all agree, and they add the wrong iformation to their trees and publish it.
Looking at that extract from the printed book, it gives Peter Hogg's date of birth as 1703. If that is correct, he cannot be the son of James Hog and Janet Blackburn because their son Peter was not born until 1719. How sure are you that the date in the book is correct? What was the date of the marriage of Peter Hogg and Elizabeth Taylor?
Looking at the information that Josephine found about William Hoge and Barbara Hume, it suggests that Barbara was born in 1667 and that William Hoge and Barbara Hume were marrid in Perth Amboy in 1688/1689 - six or seven years after he arrived in the USA.
Their son James, according to this web site, was born in 1706 in Pennsylvania and died in 1795 in Virginia. He married twice; his first wife was Agnes Crawford and his second wife was Nancy Griffith.
But no matter how accurate or inaccurate these facts may be, there does seem to be one certain fact: that is, that William Hoge and Barbara Hume had settled in the USA a good quarter of a century before James Hog and Janet Blackburn's eldest recorded child, Janet, was baptised in Scotland. And if their son James Hoge was born in the USA in 1706, he was not old enough to marry and father a child in Scotland in 1716.
Therefore it looks pretty certain to me that James Hog, husband of Janet Blackburn, cannot by any stretch of the imagination be the son of William Hoge and Barbara Hume.